Conventionally, there are various proposals of an intake device that controls an intake flow by disposing an intake control valve in an intake pipe through which the intake flow is supplied to the cylinder side of the internal combustion engines, the intake control valve forming a tumble flow (longitudinal vortex flow) or a swirl flow (lateral vortex flow). The tumble flow or the swirl flow is suitably formed in the cylinder, thereby improving combustion efficiency and an output power of the internal combustion engine. As an intake control valve employed in the intake device, there is known the intake control valve in which a valve body having a plate shape rotates about a valve shaft. The valve shaft is supported at a predetermined position of the intake passage so as to rotate the valve body, thereby changing the degree of opening and forming desirable tumble flow or swirl flow.
For example, Patent Document 1 proposes an intake device employing a cantilever-type intake control valve. Additionally, the cantilever-type intake control valve is a valve in which a valve body is provided with a valve shaft at its end and is rotated about the valve shaft. In the intake device of Patent Document 1, the valve shaft is disposed in the proximity of an inner wall of the intake passage, so the cantilever-type intake control valve is rotated. Then, this intake device has valve drive means. The valve drive means brings the intake control valve to be fully closed at the range of low speed and low load. The valve drive means brings the intake control valve to be half opened at the range of low speed and middle load, at the range of middle speed and middle load, and at the range of middle speed and low load. The valve drive means brings the intake control valve to be fully opened at the range of the high speed and the high load. Therefore, the intake device of the Patent document 1 controls the intake flow in stages by appropriately rotating the valve body about the valve shaft.
Patent Document 1: Japanese Patent application Publication No. 07-174028